1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming unit which can be employed in this image forming apparatus.
2. Description of the Related Art
There has been known an image forming apparatus employed as a copier, a printer and further a facsimile machine. The image forming apparatus of this type forms an electrostatic latent image on the circumferential surface of a photoconductive drum (image bearing member) based on image information read or transmitted from an external computer or the like. The image forming apparatus causes a developing device to supply toner toward the electrostatic latent image on the circumferential surface of the photoconductive drum, thereby forming a toner image on this circumferential surface and transfers this toner image to a sheet.
Such an image forming apparatus includes a neutralizer for neutralizing electric charges remaining on the circumferential surface of the photoconductive drum after an image transferring process to a sheet or a transfer member such as a transfer belt. The circumferential surface of the image bearing member where no electric charges are present due to the neutralization by the neutralizer heads for a charger at a downstream side, where a charging process is applied as a preparation for forming a new electrostatic latent image.
The neutralizer normally includes a substrate formed with a specified circuit and a light emitting member such as an LED (light emitting diode) attached to this substrate for obtaining power from the circuit. Accordingly, upon receiving the supply of power, the circuit and the light emitting member generate heat, whereby a negative influence may be exerted on surrounding devices due to a temperature increase. Specifically, scattered toner may attach to the surrounding devices whose temperatures have risen such as a driving mechanism to be melted and may, thereafter, be solidified to hinder normal driven states of the surrounding devices. If this occurs, a normal image forming process can be no longer performed to cause an image failure.
In order to solve such a problem, an image forming apparatus disclosed in Japanese Unexamined Patent Publication No. 2000-293090 includes a cooling device provided with a circulating air duct constructed to include a neutralizer, a fan installed in this circulating air duct and a heat pipe for cooling an air stream circulating in the circulating air duct by the driving of the fan by heat exchange.
By employing such a cooling device, heat generated in the neutralizer is removed by heat exchange with the air stream circulating in the circulating air duct by the driving of the fan. In this way, the air stream whose temperature has risen is cooled by the heat pipe and circulates in the duct. Since the neutralizer is cooled by doing so, negative influence caused by the heat generation of the neutralizer is eliminated.
However, with the cooling device disclosed in patent literature 1, the large circulating air duct, fan, heat pipe and the like have to be provided in the image forming apparatus, which causes a cost increase of the apparatus.
Accordingly, in order to solve this problem, such a long frame as to horizontally cross an apparatus body is mounted in an image forming apparatus and a specified number of neutralizers are juxtaposed atop this frame in some cases. By doing so, heat generated by the neutralizers is radiated after being transferred to the frame with a large heat radiation area, wherefore it is expected to effectively suppress temperature increases of the neutralizers.
However, an expected cooling effect cannot be obtained simply by providing the long frame and mounting the neutralizers on the frame. Therefore, a further improvement is expected.